. >>> vice president joe biden is in japan tonight at the start of a week-long trip through asia. he is standing united with japan in a growing territorial dispute with china. alfonzo has the latest from london. >> reporter: when vice president joe biden stepped off his plane in tokyo, he stepped into an escalating dispute between japan and neighboring china. >> we, the united states, deeply concerned by the attempt to unilaterally change the status quo in east china sea. >> the united states and japan say kentucky china is setting up a new air defense zone over the east china sea. an area japan claims it controls. the vice president talked about the dispute as he met with japan's prime minister. >> this action has raised regional tensions and increased the risk of accidents and miscalculation. >> the united states put its own b52's into the zone last week in a move to show that washington doesn't recognize china's claim. but, the u.s. told u.s. commercial airlines to give notice of their flight plan ahead of time. the zone measures about 600 miles from north to south above intern